Amulet of Shinnok
The Amulet of Shinnok was among the most potent of mystic talisman within the realms. Millenia ago, Shinnok concentrated his power within it, in a bid to control the realms. He was only narrowly thwarted by Raiden.
It would thereafter continue to be play a major role in the various Mortal Kombats and struggles for the realms; most notably, during the events of Mortal Kombat 4, when Shinnok would rise from the Netherealm in another bid for total conquest.
What has become of the Amulet of Shinnok and the danger it poises remains uncertain.